After importing an obj file, I cant enable smooth shading, or at least it doesn't do anything
So the problem you have here is that the entire model is ripped. If the mesh is not connected cant be smoothed out. In order to solve this, you have to select everything and remove doubles or as it is called now (merge by distance) by pressing Alt+M. Done that the mash will be messed up, with everything still selected press Shift+N to recalculate the Normals. Now if you press smooth shading the mesh should be good to go.